Intermediate rate atomic trajectories of RNA by solid-state NMR spectroscopy

Area of Science:

• Biochemistry
• Molecular Biology
• Structural Biology

Background:

• Large conformational changes are crucial for RNA function.
• Nanosecond-microsecond RNA dynamics are difficult to study with traditional methods.
• Previous studies suggested domain motions in HIV-1 TAR RNA but lacked rate information.

Purpose of the Study:

• To quantitatively describe residue trajectories in HIV-1 TAR RNA.
• To investigate RNA functional dynamics on the nanosecond-microsecond timescale.
• To elucidate the mechanism of protein-RNA recognition.

Main Methods:

• Solid-state deuterium NMR spectroscopy was employed.
• Deuterium line shape and relaxation data were analyzed.
• Motional models were developed for key residues in the TAR binding interface.

Main Results:

• Key residues in the HIV-1 TAR RNA bulge sample both free and Tat-bound conformations.
• These conformational sampling events occur on the microsecond timescale.
• The observed dynamics occur independently of protein binding.

Conclusions:

• Results support a conformational capture model for protein-RNA recognition.
• Proteins do not induce new RNA structures but bind pre-existing conformations.
• This mechanism is essential for understanding RNA functional dynamics.